Ink jet printing is a well-known technique by which printing is accomplished without contact between the printing device and the substrate on which the printed characters are deposited. Briefly described, ink jet printing involves the technique of projecting a stream of ink droplets to a surface and controlling the direction of the stream so that the droplets are caused to form the desired printed image on that surface.
In general, an ink jet ink composition should meet certain requirements to be useful in ink jet printing operations. These relate to viscosity and resistivity of the ink, the solubility and compatibility of the components, and/or the wettability of the substrate. Further, the ink should be quick drying and smear resistant, and be capable of passing through the ink jet nozzle(s) without clogging, and permit rapid cleanup of the machine components with minimum effort. The printed message or image should also resist abrasion.
When printing in the drop-on-demand mode employing certain ink jet ink compositions on substrates which retain high static electric charges, such as polyethylene and polyvinyl chloride shrink wrap packaging materials, the printer nozzle tends to clog up more frequently than normal. The ink builds up around the nozzle on the nozzle plate. This leads to poor quality images. The printer nozzle requires periodic cleaning, which leads to more frequent printer down time. The foregoing shows that there exists a need for an ink jet ink composition that can provide improved quality of images on such substrates. There is also a need to reduce the incidence of ink build up and printer nozzle clogging.
The invention provides such a composition. The advantages of the invention, as well as additional inventive features, will be apparent from the description of the invention provided herein.